WSDL 2.0 approved

The World Wide Web Consortium (W3C) is announcing Wednesday that it has completed work on the WSDL 2.0 Web services standard, which expands HTTP and SOAP support for Web applications.

Thusly, WSDL (Web Services Description Language) 2.0 is now an official W3C Recommendation, which is the equivalent of a W3C standard.

WSDL 2.0 incorporates improvements for WSDL 1.1 found in the WS-I (Web Services Interoperability Organization) Basic Profile and builds in inheritance, import functions and improved description of faults and errors, W3C said.

"It's been a long time in development, but developers can see it's been worth the wait," said Jonathan Marsh, co-chair of the W3C Web Services Description Working Group and director of Mashup Technologies at WSO2, in a statement released by W3C.

"In addition to the rigorous interoperability testing, we're pleased to have given developers the HTTP binding, which provides simple Web-friendly access to a service when the advanced features available in the SOAP stack, such as WS-Addressing, WS-Security, and WS-ReliableMessaging aren't required," Marsh said.

With the complete HTTP binding, WSDL 2.0 will work with REST (Representational State Transfer) applications without any technical obstacle, according to W3C.

WSDL 2.0 shores up some weaknesses but issues remain for SOA deployments, said Jason Bloomberg, senior analyst at ZapThink.

"WSDL 2.0 is an important revision in the most central Web services standard and will ease many of the problems facing Web services developers," Bloomberg said in an email. "It cleans up many details like fault-handling, semantics and terminology and it does add better REST support, which is useful for Web service developers who wish to work with HTTP and who don't need the more advanced capabilities SOAP brings to the table."

WSDL 2.0 presents challenges for SOA implementations because "it still lacks robust requirements for service consumers as well as nonfunctional requirements for Web services such as quality of service," Bloomberg said.

"As a result, service contracts must expand beyond the limitations of WSDL 2.0 to include all the requirements necessary to provide loose coupling between Service providers and consumers over time," he said.

WSDL 2.0 support is built into emerging Web services standards including Semantic Annotations for WSDL (SAWSDL) and WS-Policy 1.5, both of which are anticipated to be completed by W3C in September.

Among the companies planning to support WSDL 2.0 in upcoming product releases include Adobe Systems, IBM, Sun Microsystems and WSO2, W3C said.

Copyright © 2007 IDG Communications, Inc.